Multidrug Resistance In Cancer Cells Research Articles

Redefine the role of d-α-Tocopheryl polyethylene glycol 1000 succinate on P-glycoprotein, multidrug resistance protein 1, and breast cancer resistance protein mediated cancer multidrug resistance

Cancer drug resistance is an ever-changing problem that most patients need to face in their later stages of treatment, especially the multidrug resistant (MDR) type. The drug efflux transporters, including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and breast cancer resistance protein (BCRP), play the crucial roles in this sophisticated battle. In recent decades, researchers try to find potential inhibitors to impede the drug efflux function of above transporters. d-α-Tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) is a prevalently used excipient in the formulation design. In the present study, the modulatory effects and mechanisms of vitamin E TPGS on the efflux transporters were investigated. And the cancer MDR reversing ability of vitamin E TPGS was evaluated as well. Stable-cloned transporter over-expressed cell lines were used for mechanisms study, while several types of MDR cancer cell lines were adopted as reversing evaluation models. The results exhibited that vitamin E TPGS significantly inhibited the efflux function of P-gp, MRP1, and BCRP under non-cytotoxic concentrations, but not influencing the protein expression levels. Through efflux assay and molecular docking, vitamin E TPGS was found to be an uncompetitive, non-competitive, and competitive inhibitor on chemotherapeutic drug doxorubicin efflux in P-gp, MRP1, and BCRP over-expressing cell lines, respectively. Furthermore, the basal ATPase activity of three transporters were significantly inhibited by vitamin E TPGS at 10 μM. And the cell membrane fluidity of P-gp over-expressing cell line was enhanced by 22.58% with 5 μM vitamin E TPGS treatment, compared to the parental Flp-In™-293 cell line (without P-gp). The resistance reversing ability of vitamin E TPGS was prominent in MCF-7/DOX MDR breast cancer cell line, which over-expressed P-gp, MRP1, and BCRP. These significant results suggested that vitamin E TPGS is a promising modulator on transporters mediated cancer MDR. Vitamin E TPGS is not an inert excipient, but possesses MDR-reversing pharmacological effects, and deserves a re-purposing application on the future combinatorial regimen design for MDR cancer treatment.

Single-sized N-functionality graphene quantum dot in tunable dual-modality near infrared–I/II illumination detection and photodynamic therapy under multiphoton nonlinear excitation

Doping sorted graphene quantum dots (GQDs) with heteroatoms and functionalizing them with amino acid could improve their radiative recombination and two-photon properties—including their excitation-wavelength-independent photoluminescence from the ultraviolet to the near-infrared-I (NIR-I) region, absorption, quantum yield, absolute cross section, lifetime, and radiative-to-nonradiative decay ratio—under two-photon excitation (TPE) at a low excitation energy and short photoexcitation duration, as determined using a self-made optical microscopy system with a femtosecond Ti–sapphire laser. Four types of sorted GQDs were investigated: undoped GQDs, nitrogen-doped GQDs (N-GQDs), amino-functionalized GQDs (amino-GQDs), and N-doped and amino-functionalized GQDs (amino-N-GQDs). Among them, the sorted amino-N-GQDs are effective as a two-photon photosensitizer and generate the highest quantity of reactive oxygen species for the elimination of multidrug-resistant cancer cells through two-photon photodynamic therapy (PDT). Larger amino-N-GQDs result in a greater number of C–N and N–functionalities, leading to a superior photochemical effect and more favorable intrinsic luminescence properties, making the dots effective contrast agents for tracking and localizing cancer cells during in-depth bioimaging in a three-dimensional biological environment under TPE in the NIR-II region. Overall, this study highlights the potential of large amino-N-GQDs as a material for future application to dual-modality two-photon PDT and biomedical imaging.

Synthesis and in Vitro Cytotoxicity Evaluation of Jadomycins.

Jadomycins, which are benzo[b]phenanthridine-type alkaloids isolated from Streptomyces venezuelae ISP5230, exhibit cytotoxic activity against multidrug-resistant breast cancer cells. We have previously achieved the total synthesis of jadomycins using the direct arylation of juglone as a key step. In this study, we achieved the total synthesis of jadomycin T and jadomycin aglycons using L-threonine and 1-amino-2-propanol as nitrogen sources. Additionally, we evaluated the cytotoxic activity of eight compounds, including glycosides, jadomycin T, and their corresponding aglycons, in eight types of tumor cells. The evaluated jadomycins tended to exhibit stronger cytotoxic activity as aglycons than as glycosides. Although the presence of a 1,3-oxazolidine ring derived from an amino acid was not essential, the presence of the 1,3-oxazolidine ring showed strong activity when the ring had a carboxyl group. Furthermore, compared to the non-natural isomer at a different position on the phenolic hydroxyl group, the naturally occurring phenanthroviridin aglycon exhibited stronger cytotoxic activity. In addition, this study suggests that jadomycins may become lead compounds for the treatment of brain tumors; however, further studies on their ability to penetrate the blood-brain barrier are required.

Cannabis sativa mediated palladium nanoparticles as an effective nanodrug against multi-drug resistant bacteria and A549 lung cancer cells

The present paper reports a biogenic synthesis of palladium nanoparticles (PdNPs) involving Cannabis sativa leaf extract. The physicochemical characterisations of biogenic synthesised PdNPs were carried out to determine size, shape, morphology, atomic composition, and crystal structure via different techniques involving Ultraviolet–visible (UV–vis), Fourier transform infrared (FT-IR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), and X-ray diffraction (XRD). The standard particle size of the synthesized PdNPs was found to be 3.49 ± 0.5 nm from the TEM analysis, while XRD analysis showed a crystal size of 4.6 nm with a face-centred-cubic (fcc) structure. FT-IR study of the green synthesis confirmed the presence of phytochemicals which act as reducing and stabilising agents. The synthesised biogenic PdNPs were subjected to antimicrobial analysis for isolated strains of multi-drug resistant (MDR) Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Salmonella abony where minimum inhibitory concentration (MIC) was found in the range of 52.04–68.3 μg/mL. Moreover, for the cytotoxic effects of biogenic PdNPs, A549 lung cell lines were used, and the half-maximal inhibitory concentration (IC50) value was evaluated as 22.17 µg/mL. The present investigation suggests the possible role of C. sativa extract capped PdNPs in the clinical management of lung cancer cells and MDR pathogens.

Structural Basis of the Allosteric Inhibition of Human ABCG2 by Nanobodies

ABCG2 is an ATP-binding cassette transporter that exports a wide range of xenobiotic compounds and has been recognized as a contributing factor for multidrug resistance in cancer cells. Substrate and inhibitor interactions with ABCG2 have been extensively studied and small molecule inhibitors have been developed that prevent the export of anticancer drugs from tumor cells. Here, we explore the potential for inhibitors that target sites other than the substrate binding pocket of ABCG2. We developed novel nanobodies against ABCG2 and used functional analyses to select three inhibitory nanobodies (Nb8, Nb17 and Nb96) for structural studies by single particle cryo-electron microscopy. Our results showed that these nanobodies allosterically bind to different regions of the nucleotide binding domains. Two copies of Nb8 bind to the apex of the NBDs preventing them from fully closing. Nb17 binds near the two-fold axis of the transporter and interacts with both NBDs. Nb96 binds to the side of the NBD and immobilizes a region connected to key motifs involved in ATP binding and hydrolysis. All three nanobodies prevent the transporter from undergoing conformational changes required for substrate transport. These findings advance our understanding of the molecular basis of modulation of ABCG2 by external binders, which may contribute to the development of a new generation of inhibitors. Furthermore, this is the first example of modulation of human multidrug resistance transporters by nanobodies.

Statistical optimization of environmental factors to produce the cytotoxic enniatins H, I and MK1688 against human multidrug resistance cancer cell lines.

The environmental conditions were optimized to produce the enniatin H, I, and MK1688 by Fusarium strain on cereal grain exhibiting anti-carcinogenic potential against MES-SA (human uterine sarcoma cell line), HCT15 (human colorectal carcinoma cancer cell line), and their multidrug resistance sublines. From the statistical optimization by response surface methodology, the optimal condition of independent variables affecting the response variables were 20.85°C (temperature), 46.85% (w/w, initial moisture content), and 18.42days (growth time) for ENN H; 23.31°C, 44.15% (w/w) and 17.23days for ENN I; 23.08°C, 43.97% (w/w) and 17.06days for ENN MK1688. In case of cytotoxic effects, ENNs significantly suppressed growth of cancer cell lines without multidrug resistance, and ENN I inhibited growth of cancer cell lines most strongly. These data will provide valuable point to produce the cyclic hexadepsipeptide exhibiting anti-carcinogenic potential from Fusarium strains.

Hypophyllanthin and Phyllanthin from Phyllanthus niruri Synergize Doxorubicin Anticancer Properties against Resistant Breast Cancer Cells.

Doxorubicin (DOX) is a cornerstone chemotherapeutic agent for the treatment of several malignancies such as breast cancer; however, its activity is ameliorated by the development of a resistant phenotype. Phyllanthus species have been studied previously for their potential anticancer properties. The current work is aimed to study the potential cytotoxicity and chemomodulatory effects of hypophyllanthin (PN4) and phyllanthin (PN5) isolated from Phyllanthus niruri to DOX against the adriamycin multidrug-resistant breast cancer cells (MCF-7ADR) and elucidate their mechanism of action. The major compounds of the active methylene chloride fraction were isolated and assessed for their potential cytotoxicity and chemomodulatory effects on DOX against naïve (MCF-7) and resistant breast (MCF-7ADR) cancer cells. The mechanism of action of both compounds in terms of their impacts on programmed/non-programmed cell death (apoptosis and autophagy/necrosis), cell cycle progression/arrest, and tumor cell migration/invasion was investigated. Both compounds PN4 and PN5 showed a moderate but similar potency against MCF-7 as well as MCF-7ADR and significantly synergized DOX-induced anticancer properties against MCF-7ADR. The chemomodulatory effect of both compounds to DOX was found to be via potentiating DOX-induced cell cycle interference and apoptosis induction. It was found that PN4 and PN5 blocked the apoptosis-escape autophagy pathway in MCF-7ADR. On the molecular level, both compounds interfered with SIRT1 expression and consequently suppressed Akt phosphorylation, and PN5 blocked apoptosis escape. Furthermore, PN4 and PN5 showed promising antimigratory and anti-invasive effects against MCF-7ADR, as confirmed by suppression of N-cadherin/β-catenin expression. In conclusion, for the first time, hypophyllanthin and phyllanthin isolated from P. niruri showed promising chemomodulatory effects to the DOX-induced chemotherapeutic activity against MCF-7ADR. Both compounds significantly synergized DOX-induced anticancer properties against MCF-7ADR. This enhanced activity was explained by further promoting DOX-induced apoptosis and suppressing the apoptosis-escape autophagy feature of the resistant breast cancer cells. Both compounds (hypophyllanthin and phyllanthin) interfered with the SIRT1/Akt pathway and suppressed the N-cadherin/β-catenin axis, confirming the observed antiproliferative, cytotoxic, and anti-invasive effects of hypophyllanthin and phyllanthin.

In-Silico Mining of the Toxins Database (T3DB) towards Hunting Prospective Candidates as ABCB1 Inhibitors: Integrated Molecular Docking and Lipid Bilayer-Enhanced Molecular Dynamics Study.

Multidrug resistance (MDR) is one of the most problematic issues in chemotherapeutic carcinoma therapy. The ABCB1 transporter, a drug efflux pump overexpressed in cancer cells, has been thoroughly investigated for its association with MDR. Thus, discovering ABCB1 inhibitors can reverse the MDR in cancer cells. In the current work, a molecular docking technique was utilized for hunting the most prospective ABCB1 inhibitors from the Toxin and Toxin-Target Database (T3DB). Based on the docking computations, the most promising T3DB compounds complexed with the ABCB1 transporter were subjected to molecular dynamics (MD) simulations over 100 ns. Utilizing the MM-GBSA approach, the corresponding binding affinities were computed. Compared to ZQU (calc. -49.8 kcal/mol), Emamectin B1a (T3D1043), Emamectin B1b (T3D1044), Vincristine (T3D4016), Vinblastine (T3D4017), and Vindesine (T3D2479) complexed with ABCB1 transporter demonstrated outstanding binding affinities with ΔGbinding values of -93.0, -92.6, -93.8, -92.2, and -90.8 kcal/mol, respectively. The structural and energetic investigations confirmed the constancy of the identified T3DB compounds complexed with the ABCB1 transporter during the 100 ns MD course. To mimic the physiological conditions, MD simulations were conducted for those identified inhibitors complexed with ABCB1 transporter in the presence of a POPC membrane. These findings revealed that Emamectin B1a, Emamectin B1b, Vincristine, Vinblastine, and Vindesine are promising ABCB1 inhibitors that can reverse the MDR. Therefore, subjecting those compounds to further in-vitro and in-vivo investigations is worthwhile.

The AKT inhibitor, MK-2206, attenuates ABCG2-mediated drug resistance in lung and colon cancer cells.

Introduction: The overexpression of ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, are two of the major mediators of multidrug resistance (MDR) in cancers. Although multiple ABCB1 and ABCG2 inhibitors have been developed and some have undergone evaluation in clinical trials, none have been clinically approved. The compound, MK-2206, an inhibitor of the protein kinases AKT1/2/3, is undergoing evaluation in multiple clinical trials for the treatment of certain types of cancers, including those resistant to erlotinib. In this in vitro study, we conducted in vitro experiments to determine if MK-2206 attenuates multidrug resistance in cancer cells overexpressing the ABCB1 or ABCG2 transporter. Methodology: The efficacy of MK-2206 (0.03-1μM), in combination with the ABCB1 transporter sub-strates doxorubicin and paclitaxel, and ABCG2 transporter substrates mitoxantrone, SN-38 and topotecan, were determined in the cancer cell lines, KB-C2 and SW620/Ad300, which overexpress the ABCB1 transporter or H460/MX20 and S1-M1-80, which overexpress the ABCG2 transporter, respectively. The expression level and the localization of ABCG2 transporter on the cancer cells membranes were determined using western blot and immunofluorescence assays, respectively, following the incubation of cells with MK-2206. Finally, the interaction between MK-2206 and human ABCG2 transporter was predicted using computer-aided molecular modeling. Results: MK-2206 significantly increased the efficacy of anticancer compounds that were substrates for the ABCG2 but not the ABCB1 transporter. MK-2206 alone (0.03-1μM) did not significantly alter the viability of H460/MX20 and S1-M1-80 cancer cells, which overexpress the ABCG2 transporter, compared to cells incubated with vehicle. However, MK-2206 (0.3 and 1μM) significantly increased the anticancer efficacy of mitoxantrone, SN-38 and topotecan, in H460/MX20 and S1-M1-80 cancer cells, as indicated by a significant decrease in their IC50 values, compared to cells incubated with vehicle. MK-2206 significantly increased the basal activity of the ABCG2 ATPase (EC50 = 0.46μM) but did not significantly alter its expression level and sub-localization in the membrane. The molecular modeling results suggested that MK-2206 binds to the active pocket of the ABCG2 transporter, by a hydrogen bond, hydrophobic interactions and π-π stacking. Conclusion: These in vitro data indicated that MK-2206 surmounts resistance to mitoxantrone, SN-38 and topotecan in cancer cells overexpressing the ABCG2 transporter. If these results can be translated to humans, it is possible that MK-2206 could be used to surmount MDR in cancer cells overexpressing the ABCG2 transporter.

Decursinol Angelate Inhibits Glutamate Dehydrogenase 1 Activity and Induces Intrinsic Apoptosis in MDR-CRC Cells.

Colorectal cancer (CRC) was the second most commonly diagnosed cancer worldwide and the second most common cause of cancer-related deaths in Europe in 2020. After CRC patients' recovery, in many cases a patient's tumor returns and develops chemoresistance, which has remained a major challenge worldwide. We previously published our novel findings on the role of DA in inhibiting the activity of GDH1 using in silico and enzymatic assays. No studies have been conducted so far to explain the inhibitory role of DA against glutamate dehydrogenase in MDR-CRC cells. We developed a multidrug-resistant colorectal cancer cell line, HCT-116MDR, after treatment with cisplatin and 5-fluorouracil. We confirmed the MDR phenotype by evaluating the expression of MDR1, ABCB5, extracellular vesicles, polyploidy, DNA damage response markers and GDH1 in comparison with parental HCT-116WT (HCT-116 wild type). Following confirmation, we determined the IC50 and performed clonogenic assay for the efficacy of decursinol angelate (DA) against HCT-116MDR (HCT-116 multidrug resistant). Subsequently, we evaluated the novel interactions of DA with GDH1 and the expression of important markers regulating redox homeostasis and cell death. DA treatment markedly downregulated the expression of GDH1 at 50 and 75 μM after 36 h, which directly correlated with reduced expression of the Krebs cycle metabolites α-ketoglutarate and fumarate. We also observed a systematic dose-dependent downregulation of MDR1, ABCB5, TERT, ERCC1 and γH2AX. Similarly, the expression of important antioxidant markers was also downregulated. The markers for intrinsic apoptosis were notably upregulated in a dose-dependent manner. The results were further validated by flow cytometry and TUNEL assay. Additionally, GDH1 knockdown on both HCT-116WT and HCT-116MDR corresponded to a decreased expression of γH2AX, catalase, SOD1 and Gpx-1, and an eventual increase in apoptosis markers. In conclusion, inhibition of GDH1 increased ROS production, decreased cell proliferation and increased cell death.

A cycloruthenated complex, ruthenium (II) Z (RuZ) overcomes in vitro and in vivo multidrug resistance in cancer cells: A pivotal breakthrough.

A cycloruthenated complex, ruthenium (II) Z (RuZ) overcomes in vitro and in vivo multidrug resistance in cancer cells: A pivotal breakthrough.

Reversal of P-glycoprotein-mediated multidrug resistance by natural N-alkylated indole alkaloid derivatives in KB-ChR-8-5 drug-resistant cancer cells.

Multidrug resistance (MDR) remains a significant challenge in cancer chemotherapy due to the overexpression of ATP-binding cassette drug-efflux transporters, namely P-glycoprotein (P-gp)/ATP-binding cassette subfamily B member 1. In this study, derivatives of N-alkylated monoterpene indole alkaloids such as N-(para-bromobenzyl) (NBBT), N-(para-methylbenzyl) (NMBT), and N-(para-methoxyphenethyl) (NMPT)moieties were investigated for the reversal of P-gp-mediated MDRin drug-resistant KB colchicine-resistant 8-5(KB-ChR-8-5) cells. Among the three indole alkaloid derivatives, the NBBT exhibited the highest P-gp inhibitory activity in a dose-dependent manner. Further, it significantly decreased P-gp overexpression by inactivating the nuclear translocation of the nuclearfactor kappa B p-50 subunit. In the cell survival assay, doxorubicin showed 6.3-fold resistance (FR) in KB-ChR-8-5 cells compared with its parental KB-3-1 cells. However, NBBT significantly reduced doxorubicin FR to 1.7, 1.3, and 0.4 and showed strong synergism with doxorubicin for all the concentrations studied in the drug-resistant cells. Furthermore, NBBT and doxorubicin combination decreased the cellular migration and showed increased apoptotic incidence by downregulating Bcl-2, then activating BAX, caspase 3, and p53. The present findings suggest that NBBT could be a lead candidate for the reversal of P-gp- mediated multidrug resistance in cancer cells.

Early in vitro evidence indicates that deacetylated sialic acids modulate multi-drug resistance in colon and lung cancers via breast cancer resistance protein.

Cancers utilize sugar residues to engage in multidrug resistance. The underlying mechanism of action involving glycans, specifically the glycan sialic acid (Sia) and its various functional group alterations, has not been explored. ATP-binding cassette (ABC) transporter proteins, key proteins utilized by cancers to engage in multidrug resistant (MDR) pathways, contain Sias in their extracellular domains. The core structure of Sia can contain a variety of functional groups, including O-acetylation on the C6 tail. Modulating the expression of acetylated-Sias on Breast Cancer Resistance Protein (BCRP), a significant ABC transporter implicated in MDR, in lung and colon cancer cells directly impacted the ability of cancer cells to either retain or efflux chemotherapeutics. Via CRISPR-Cas-9 gene editing, acetylation was modulated by the removal of CAS1 Domain-containing protein (CASD1) and Sialate O-Acetyl esterase (SIAE) genes. Using western blot, immunofluorescence, gene expression, and drug sensitivity analysis, we confirmed that deacetylated Sias regulated a MDR pathway in colon and lung cancer in early in vitro models. When deacetylated Sias were expressed on BCRP, colon and lung cancer cells were able to export high levels of BCRP to the cell's surface, resulting in an increased BCRP efflux activity, reduced sensitivity to the anticancer drug Mitoxantrone, and high proliferation relative to control cells. These observations correlated with increased levels of cell survival proteins, BcL-2 and PARP1. Further studies also implicated the lysosomal pathway for the observed variation in BCRP levels among the cell variants. RNASeq data analysis of clinical samples revealed higher CASD1 expression as a favorable marker of survival in lung adenocarcinoma. Collectively, our findings indicate that deacetylated Sia is utilized by colon and lung cancers to engage in MDR via overexpression and efflux action of BCRP.

Functionalized liposomes for targeted breast cancer drug delivery.

Despite the exceptional progress in breast cancer pathogenesis, prognosis, diagnosis, and treatment strategies, it remains a prominent cause of female mortality worldwide. Additionally, although chemotherapies are effective, they are associated with critical limitations, most notably their lack of specificity resulting in systemic toxicity and the eventual development of multi-drug resistance (MDR) cancer cells. Liposomes have proven to be an invaluable drug delivery system but of the multitudes of liposomal systems developed every year only a few have been approved for clinical use, none of which employ active targeting. In this review, we summarize the most recent strategies in development for actively targeted liposomal drug delivery systems for surface, transmembrane and internal cell receptors, enzymes, direct cell targeting and dual-targeting of breast cancer and breast cancer-associated cells, e.g., cancer stem cells, cells associated with the tumor microenvironment, etc.

Medicago Sativa Defensin1 as a tumor sensitizer for improving chemotherapy: translation from anti-fungal agent to a potential anti-cancer agent.

Plant defensins including Medicago Sativa defensin 1 (MsDef1) are cysteine-rich antifungal peptides which are known for potent broad-spectrum antifungal activity against bacterial or fungal pathogens of plants. The antimicrobial activities of these cationic defensins are attributed to their capacity to bind to cell membranes to create potentially structural defects tin the cell membranes to interact with intracellular target (s) and mediates cytotoxic effects. Our earlier work identified Glucosylceramide (GlcCer) of fungus F. graminearum as a potential target for biological activity. Multi-drug resistant (MDR) cancer cells overexpress GlcCer on the surface of plasma membrane. Hence, MsDef1 may have a potential to bind to GlcCer of MDR cancer cells to induce cell death. We have characterized the three-dimensional structure of MsDef1 and the solution dynamics using of 15N-labeled MsDef1 nuclear magnetic resonance (NMR) spectroscopy which showed that GlcCer binds MsDef1 at two specific sites on the peptide molecule. The ability of MsDef1 to permeate MDR cancer cells was demonstrated by measuring the release of apoptotic ceramide in drug resistant MCF-7R cells. It was also shown that MsDef1 activated dual cell death pathways ceramide and Apoptosis Stimulating Kinase ASK1 by disintegrating GlcCer and oxidizing tumor specific biomarker thioredoxin (Trx) respectively. As a result, MsDef1 sensitizes MDR cancer cells to evoke a better response from Doxorubicin, a front-line chemotherapy for triple negative breast cancer (TNBC) treatment. The combination of MsDef1 and Doxorubicin induced 5 to10-fold greater apoptosis in vitro MDR cells MDA-MB-231R compared to either MsDef1 or Doxorubicin alone. Confocal microscopy revealed that MsDef1 facilitates a) influx of Doxorubicin in MDR cancer cells, b) preferential uptake by MDR cells but not by normal fibroblasts and breast epithelial cells (MCF-10A). These results suggest that MsDef1 targets MDR cancer cells and may find utility as a neoadjuvant chemotherapy. Hence, the extension of antifungal properties of MsDef1 to cancer my result in addressing the MDR problems in cancer.

Design, Synthesis, and Antiproliferative Activity of Benzopyran-4-One-Isoxazole Hybrid Compounds.

The biological significance of benzopyran-4-ones as cytotoxic agents against multi-drug resistant cancer cell lines and isoxazoles as anti-inflammatory agents in cellular assays prompted us to design and synthesize their hybrid compounds and explore their antiproliferative activity against a panel of six cancer cell lines and two normal cell lines. Compounds 5a-d displayed significant antiproliferative activities against all the cancer cell lines tested, and IC50 values were in the range of 5.2-22.2 μM against MDA-MB-231 cancer cells, while they were minimally cytotoxic to the HEK-293 and LLC-PK1 normal cell lines. The IC50 values of 5a-d against normal HEK-293 cells were in the range of 102.4-293.2 μM. Compound 5a was screened for kinase inhibitory activity, proteolytic human serum stability, and apoptotic activity. The compound was found inactive towards different kinases, while it completely degraded after 2 h of incubation with human serum. At 5 μM concentration, it induced apoptosis in MDA-MB-231 by 50.8%. Overall, these findings suggest that new benzopyran-4-one-isoxazole hybrid compounds, particularly 5a-d, are selective anticancer agents, potentially safe for human cells, and could be synthesized at low cost. Additionally, Compound 5a exhibits potential anticancer activity mediated via inhibition of cancer cell proliferation and induction of apoptosis.

Diterpenoids with an unusual tricyclo[10.3.0.02,9]pentadecane skeleton from Pedilanthus tithymaloides as multidrug resistance modulators

Three new diterpenoids with an unusual carbon skeleton, pedilanins A-C (1–3), and nine new jatrophane diterpenoids, pedilanins D-L (4–12), along with five known ones (13–17), were isolated from Pedilanthus tithymaloides. Compounds 1–3 characterize an unprecedented tricyclo[10.3.0.02,9]pentadecane skeleton. Compounds 4–8 are rare examples of the jatrophanes bearing a cyclic hemiketal substructure. Their structures were determined by an extensive analysis of HRESIMS, NMR, quantum-chemical calculation, DP4+ probability, and X-ray crystallographic data. In the bioassay, compounds 1–12 dramatically reversed multidrug resistance in cancer cells with the fold-reversals ranging from 17.9 to 396.8 at the noncytotoxic concentration of 10 μM. The mechanism results indicated that compounds 2 and 3 inhibited the P-glycoprotein (Pgp) transporter function, thus reversing the drug resistance.

Targeting and sensitizing MDR cancer by an MMP2 and pH dual-responsive ZnO-based nanomedicine

Zinc oxide nanoparticles (ZnO NPs) have been known as a therapeutic agent and drug delivery system for treating various diseases, including infectious diseases and cancer. However, due to the low biocompatibility, short in vivo half-life, and potential toxicity, the previous studies on ZnO NPs were mainly focused on their in vitro applications. The effective and safe ZnO NP-based systems which can be used for in vivo drug delivery have been rarely reported. In this study, we developed a novel dual-responsive hybrid ZnO NP (ZnO/DPPG/PEG-pp-PE) consisting of the ZnO NPs, phospholipid (DPPG), and enzyme-sensitive amphiphilic polymer (PEG-pp-PE), which could respond to both tumoral matrix metalloproteinase 2 (MMP2) and intracellular acidic pH, for tumor-targeted drug delivery and multidrug resistant (MDR) cancer treatment. The dual-responsive ZnO/DPPG/PEG-pp-PE could easily load the model drug, doxorubicin (DOX), and showed excellent physicochemical properties, stability, and MMP2 and pH dual sensitivity. The ZnO/DPPG/PEG-pp-PE/DOX showed the MMP2-dependent cellular uptake, enhanced cell penetration, and improved anticancer activity in the MDR cancer cells and their spheroids. In the MDR tumor-bearing mice, the ZnO/DPPG/PEG-pp-PE/DOX improved the biocompatibility, tumor targetability, and anticancer activity of DOX and ZnO without significant toxicity compared to the free DOX, ZnO/DOX, and nonsensitive ZnO NPs. The data suggested that the dual-sensitive ZnO-based nanomedicine could be a promising delivery system for targeted drug delivery and therapy against the MDR cancer.

Chemosensitizing potential of andrographolide in P-glycoprotein overexpressing multidrug-resistant cancer cell lines

The P-glycoprotein (P-gp) plays a major role in the efflux of chemotherapeutic drugs and significantly limits chemotherapy efficacy. Chemosensitizers augment the therapeutic effects of anticancer agents by overcoming drug resistance mechanisms. In this study, the chemosensitizing property of andrographolide (Andro) in P-gp overexpressing multidrug-resistant (MDR) colchicine-selected KBChR 8-5 cells was evaluated. Molecular docking studies showed Andro exhibits higher binding interaction with P-gp than the other two ABC-transporters studied. Further, it inhibits P-gp transport function in a concentration dependant manner in the colchicine-selected KBChR 8-5 cells. Moreover, Andro downregulates P-gp overexpression via NF-κB signaling in these MDR cell lines. MTT-based cell-based assay illustrates that Andro treatment augments the PTX effect in the KBChR 8-5 cells. Further, the Andro plus PTX combination showed enhanced apoptotic cell death in KBChR 8-5 cells compared with PTX alone treatment. Therefore, the results showed that Andro enhances PTX therapeutic effect in the drug-resistant KBChR 8-5 cells.

Overcoming Multidrug Resistance by Base-Editing-Induced Codon Mutation.

Multidrug resistance (MDR) is the main obstacle in cancer chemotherapy. ATP binding cassette (ABC) transporters on the MDR cell membrane can transport a wide range of antitumor drugs out of cells, which is one of the main causes of MDR. Therefore, disturbing ABC transporters becomes the key to reversing MDR. In this study, we implement a cytosine base editor (CBE) system to knock out the gene encoding ABC transporters by base editing. When the CBE system works in MDR cells, the MDR cells are manipulated, and the genes encoding ABC transporters can be inactivated by precisely changing single in-frame nucleotides to induce stop (iSTOP) codons. In this way, the expression of ABC efflux transporters is reduced and intracellular drug retention is significantly increased in MDR cells. Ultimately, the drug shows considerable cytotoxicity to the MDR cancer cells. Moreover, the substantial downregulation of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) implies the successful application of the CBE system in the knockout of different ABC efflux transporters. The recovery of chemosensitivity of MDR cancer cells to the chemotherapeutic drugs revealed that the system has a satisfactory universality and applicability. We believe that the CBE system will provide valuable clues for the use of CRISPR technology to defeat the MDR of cancer cells.